Method of molding window for display

ABSTRACT

A method of molding a window for a display device includes: forming curved side surfaces and curved corners of the window, by pressing a heated preliminary window glass to a mold. The mold includes: a flat portion corresponding to a flat display portion of the display device; a window side surface bending portion corresponding to the side surfaces of the display device; and a window corner bending portion corresponding to the corners of the display device. The forming the curved side surfaces of the window includes pressing the heated preliminary window glass against the window side surface bending portion of the mold; and after the forming of the curved side surfaces, forming the curved corners and a flat portion of the window by further pressing the heated preliminary window glass respectively against the window corner bending portion and the flat portion of the mold.

This application is a divisional application of U.S. application Ser.No. 16/233,292 filed Dec. 27, 2018, which claims priority to KoreanPatent Application No. 10-2018-0016892, filed on Feb. 12, 2018, and allthe benefits accruing therefrom under 35 U.S.C. § 119, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The present disclosure relates to a method of molding curved surfaces ofa window for a display device, and more specifically to a method whichis capable of molding the corners of the window for the display deviceinto the curved surfaces.

2. Description of the Related Art

In viewing a mobile display device, left and right edge portions of thedisplay device have not been utilized as display surfaces. However, theleft and right edge portions of a mobile display device formed intocurved surfaces has been developed, and such curved surface edgeportions are utilized as new display surfaces of the mobile displaydevice.

A left edge, right edge or two-side edge display device can beimplemented using a one- or two-curved surface window and a flexibledisplay panel. Additionally, a four-side edge display device using allfour side edges as display surfaces is also being developed.Accordingly, a display device in which four-side edges are curvedsurfaces includes a three-dimensional (“3D”) window having four curvedside edges.

A window of a curved surface display device is manufactured by thermallymolding glass such as by using one or more molds. Glass having anoriginal plate shape is formed such as by molding into a curvedsurface-shaped product having a curvature by using the viscoelasticityof glass.

SUMMARY

The present disclosure is directed to a method of molding the corners ofa window for a display device into curved surfaces from an originalnon-curved form of the glass.

According to an exemplary embodiment, there is provided a mold formolding a window for a display, the mold including: a flat portioncorresponding to a flat display portion of the display device; a windowside surface bending portion corresponding to a side surface of thedisplay device which is extended from an edge of the flat displayportion thereof; and a window corner bending portion corresponding to acorner of the display device which is extended from a corner of the flatdisplay portion thereof, where along a thickness direction of the mold,the window side surface bending portion disposes the window cornerbending portion between the flat portion and the window side surfacebending portion.

The window side surface bending portion may include an inclined surfacealong which an end portion of a preliminary window material which isflat is pressed to be inclined at a first angle relative to a lowersurface of the mold.

Contact of the inclined end portion of the preliminary window materialalong the window corner bending portion between the flat portion and thewindow side surface bending portion, may bend the inclined end portionto be curved at a second angle relative to the lower surface of themold, the second angle being smaller than the first angle.

The mold may include a plurality of partial molds each including theflat portion, the window side surface bending portion and the windowcorner bending portion.

According to another exemplary embodiment, there is provided a mold formolding a window for a display, the mold including at least one mold ofan upper mold and a lower mold, where the at least one mold includes: aflat portion corresponding to a flat display portion of the displaydevice; a window side surface bending portion corresponding to a sidesurface of the display device which is extended from an edge of the flatdisplay portion thereof; and a window corner bending portioncorresponding to a corner of the display device which is extended from acorner of the flat display portion thereof, where along a thicknessdirection of the mold, the window side surface bending portion disposesthe window corner bending portion between the flat portion and thewindow side surface bending portion.

The window side surface bending portion may include an inclined surfacealong which an end portion of the preliminary window material which isflat is pressed to be inclined at a first angle relative to a lowersurface of the mold.

Contact of the inclined end portion of the preliminary window materialalong the window corner bending portion between the flat portion and thewindow side surface bending portion, may bend the inclined end portionto be curved at a second angle relative to the lower surface of themold, the second angle being smaller than the first angle.

The mold may include a plurality of partial molds each including theflat portion, the window side surface bending portion and the windowcorner bending portion.

According to still another exemplary embodiment, there is provided amethod of molding a window for a display, the method including: formingcurved side surfaces and curved corners of the window which respectivelycorrespond to side surfaces and corners of the display device, bypressing a preliminary window glass heated to a transition pointtemperature or higher to at least one mold of an upper mold and a lowermold, where the at least one mold includes: a flat portion correspondingto a flat display portion of the display device; a window side surfacebending portion corresponding to the side surfaces of the display devicewhich are respectively extended from edges of the flat display portionthereof; and a window corner bending portion corresponding to thecorners of the display device which are respectively extended curvedfrom corners of the flat display portion thereof; the forming the curvedside surfaces of the window includes pressing the heated preliminarywindow glass against the window side surface bending portion of themold; and after the forming of the curved side surfaces, forming thecurved corners and a flat portion of the window by further pressing theheated preliminary window glass respectively against the window cornerbending portion and the flat portion of the mold.

The window side surface bending portion may include an inclined surface,and the pressing of the heated preliminary window glass against thewindow side surface bending portion may press an end portion of theheated preliminary window glass against the inclined surface to bend theend portion at a first angle relative to a lower surface of the mold.

The further pressing of the heated preliminary glass again the windowcorner bending portion may include contacting the bent end portion ofthe heated preliminary glass along the window corner bending portion tofurther bend the end portion to be curved at a second angle relative tothe lower surface of the mold, the second angle being smaller than thefirst angle.

The mold may include a plurality of partial molds each including theflat portion, the window side surface bending portion and the windowcorner bending portion.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention will become more apparentby describing in detail exemplary embodiments thereof with reference tothe accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of an exemplary embodiment ofdisplay device which is bent;

FIG. 2 is an exemplary embodiment of a cross-sectional view of the bentdisplay device of FIG. 1 ;

FIG. 3 is modified exemplary embodiment of a cross-sectional view of thebent display device of FIG. 1 ;

FIG. 4A_1 through 4A_4 are perspective views showing processes in anexemplary embodiment of a method of molding a window by using two molds;

FIG. 4B is a perspective view showing a window molded using the methodof molding a window, which is shown in FIG. 4A_1 through 4A_4;

FIGS. 5A and 5B are perspective views showing shapes of a mold which isused to mold glass;

FIG. 5C is a top plan view showing an exemplary embodiment of cornerportions of a window;

FIG. 6A is a perspective view showing an exemplary embodiment of apartial upper mold which is used to mold glass according to theinvention;

FIG. 6B is a perspective view showing an exemplary embodiment of a moldwhich is used to mold glass according to the invention;

FIG. 6C is a cross-sectional view of the partial upper mold of FIG. 6A;

FIGS. 7A and 7B are perspective and top plan views showing an exemplaryembodiment of a window molded using a method of molding a windowaccording to the invention;

FIG. 8 is a perspective view showing an exemplary embodiment of bendinglines which intersect one another at a corner portion of a window moldedusing a method of molding a window; and

FIGS. 9A to 9D respectively show exemplary embodiments of multi-surfacecorner glass windows molded using a method of molding a window accordingto the invention.

DETAILED DESCRIPTION

The advantages and features of the invention and methods for achievingthem will become apparent from exemplary embodiments described below indetail in conjunction with the accompanying drawings. However, theinvention is not limited to the following exemplary embodiments, but maybe implemented in various different forms. These exemplary embodimentsare provided merely to make the disclosure of the invention complete andto fully convey the scope of the invention to a person having ordinaryknowledge in the art to which the invention pertains. The invention isdefined only by the scope of the attached claims. Therefore, in someexemplary embodiments, well-known process steps, component structures,and technologies will not be described in detail in order to prevent thepresent disclosure from being obscurely interpreted. Throughout thespecification, the same reference symbols refer to the same components.

It will be understood that when an element is referred to as beingrelated to another element such as being “on” another element, it can bedirectly on the other element or intervening elements may be presenttherebetween. In contrast, when an element is referred to as beingrelated to another element such as being “directly on” another element,there are no intervening elements present.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “At least one” is not to be construed as limiting “a” or“an.” “Or” means “and/or.” As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.It will be further understood that the terms “comprises” and/or“comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10% or 5% of the stated value.

Unless otherwise defined, all terms used herein (including technical andscientific terms) have the same meanings as commonly understood by aperson skilled in the art to which this invention pertains. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having meanings which areconsistent with their meanings in the context of the relevant art andshould not be interpreted in an ideal or excessively formal sense unlessclearly defined in the present specification.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

A window of a curved surface display device is manufactured by thermallymolding glass such as by using one or more molds. Glass having anoriginal plate shape is formed such as by molding into a curvedsurface-shaped product having a curvature by using the viscoelasticityof glass. The technique of bending one or two surfaces of a glass shapewhich do not overlap each other has been applied to mobile productssince the implementation thereof is relatively free.

However, since at least three bending lines are used for the shape of acorner portion of a molded glass formed from three bending surfacesoverlap one another, a corner is formed at the intersection of the threebending lines, and the shape of the corner portion is formed from onglass having an original plate shape. Accordingly, it is difficult toform a desired shape of a window using overlapping surfaces.

Additionally, when all four sides of a mobile display device are formedby bending glass having an original a plate shape such as by usingmolds, changes in the tensile stress of the glass are concentrated atcorners, and thus it is difficult to control forming of a 3D shape. Inother words, there occurs a phenomenon in the glass such as a decreasein the thickness of corners or the generation of a wrinkle, the glassdrooping downward, a difference in the length of the corners, etc. andconsequently the flatness of a front portion of the glass is degraded.Therefore, it is difficult to control the dimensions of the 3D shape ofglass during molding from an original shape thereof.

Exemplary embodiments of a window of a display device and method ofmanufacturing the window according to the present disclosure will bedescribed with reference to FIGS. 1 to 9D.

FIG. 1 is an exploded perspective view of an exemplary embodiment of adisplay device which is bent, FIG. 2 is a an exemplary embodiment ofcross-sectional view of the bent display device of FIG. 1 , and FIG. 3is a modified exemplary embodiment of a cross-sectional view of the bentdisplay device of FIG. 1 .

Referring to FIGS. 1 to 3 , the bent display device may include adisplay panel 100, and a window 200 which is disposed on the displaypanel 100.

According to an exemplary embodiment of the present disclosure, thedisplay panel 100 may be a flexible display panel. Alternatively,according to an exemplary embodiment of the present disclosure, thedisplay panel 100 may be a bent display panel having bent edges.

In a method of manufacturing a bent display device, the display panel100 may be formed to have curved edges, or may be manufactured in a flatoriginal shape and for which non-curved edges thereof are subsequentlycurved such as through coupling of the display panel 100 with the window200, a fastening frame (not shown) or the like. In other words, thedisplay panel 100 may have substantially the same shape as the window200 in a finally-formed bent display device.

In the following, for ease of description, the center flat portion ofthe display panel 100 is referred to as a flat portion 101, and curvedportions along outer edges of the flat portion 101 are referred to ascurved portions 102. Although the curved portions 102 of the displaypanel 100 are illustrated as being formed along two opposite edges ofthe flat portion 101, the display panel 100 is not limited thereto. Inanother exemplary embodiment, the curved portion 102 may be disposed orformed only along one edge of the flat portion 101. The flat portion 101and the curved portions 102 are distinguished from each other for easeof description, but may define a single and continuous display area ofthe bent display device. That is, a display area at one of the flatportion 101 and a curved portion 102 may extend to define one or more ofthe remaining curved portions 102 and flat portion 101 of the final bentdisplay panel 100.

The overall bent display device and components thereof are disposed in aplane defined by first and second directions crossing each other. Athickness of the overall bent display device and components thereof isdisposed in a third direction crossing each of the first and seconddirections. In FIG. 1 , a direction in which the curved portions 102 arearranged may be a first direction, while a direction in which thenon-curved edges (except for the curved portions 102) are arranged maybe a second direction, or vice versa. In FIGS. 2 and 3 , the horizontaldirection of the views may be the first and/or second directions whilethe vertical direction of the views may be a third (thickness) directionwhich crosses each of the first and second directions.

The display panel 100 may include a pixel PX provided in plurality whichare used to generate and display images. The plurality of pixels PX maybe disposed at the flat portion 101 and one or more of the curvedportions 102 of the display panel 100, and may display images. Theplurality of pixels PX may be arranged along one or more of the first tothird directions of the overall bend display device. The plurality ofpixels PX of the flat portion 101 may be connected to pixels PX in oneor more of the curved portions 102, without being limited thereto.

The bent display device may include a display area at which an image isdisplayed, in each of the flat portion 101 and the curved portion 102.The bent display device may also include a non-display area at which theimage is not displayed, in one or more portion among the flat portion101 and the curved portion 102.

The display panel 100 may include a flexible film, such as a plasticfilm, as a base substrate or film. The display panel 100 may beimplemented in such a manner that light-generating elements such asorganic light-emitting diodes (“LEDs”), signal-transmitting lines andpixel-driving circuits are disposed on the base substrate as theflexible film.

The window 200 may be disposed on the display panel 100. The window 200may form an outermost surface of the bent display device. The window 200may form a display surface of the bent display device respectively atcorresponding display areas of the display panel 100. The window 200includes a transparent, relatively hard material, and may protect thedisplay panel 100 from external shock to the display device whiletransmitting the images of the display panel 100 therethrough.Furthermore, the window 200 may include or be manufactured using aflexible film material, such as a plastic film material.

The window 200 may have curved edges as an original-formed shape or mayhave a flat original shape which is subsequently deformed to form thecurved edges. In the following, for ease of description, the center flatportion of the window 200 is referred to as a flat portion 201, and acurved portion along one or more edges of the flat portion 201 arereferred to as a curved portion 202. Each of the overall curved portions202 may be divided into an outermost first curved portion 202 a of thewindow 200 at a distal end thereof and a second curved portion 202 bbetween the flat portion 201 and the first curved portion 202 a.

Although the curved portions 202 of the window 200 are illustrated asbeing formed along two opposite edges of the flat portion 201, thewindow 200 is not limited thereto. In another exemplary embodiment, thecurved portion 202 may be disposed or formed only along one edge of theflat portion 201. The flat portion 201, the first curved portions 202 a,and the second curved portions 202 b are distinguished from each otherfor ease of description, but may be actually a single continuous area.That is, a planar area at one of the flat portion 201 and a curvedportion 202 may extend to define one or more of the remaining curvedportions 202 and flat portion 201 of the final bent window 200.

Although the curved portions 202 are described on the assumption thateach of the curved portions 202 has the first curved portion 202 a andthe second curved portion 202 b, the curved portions 202 are not limitedthereto. In an exemplary embodiment, each of the curved portions 202 mayinclude two or more portions which are disposed adjacent to each otherin a direction perpendicular to a bending direction, such as in adirection away from the flat portion 201.

The first curved portions 202 a and the second curved portions 202 b mayhave substantially the same curvature. More specifically, a preliminaryflat portion and the first curved portions 202 a may be formed bybending two opposite edge portions at distal ends thereof (e.g., areasin which the first curved portions 202 a will be formed) of an originalflat-shaped material for forming a window, and the flat portion 201 andthe second curved portions 202 b may be formed by bending two oppositeedge portions (e.g., areas in which the second curved portions 202 bwill be formed) of the preliminary flat portion at a predeterminedcurvature. The method of forming the first curved portions 202 a and thesecond curved portions 202 b will be described in greater detail later.

In the window 200, the angle between the longitudinal section of theflat portion 201 and the longitudinal section of the curved portions 202may be an obtuse angle. In an exemplary embodiment, the angle betweenthe longitudinal section of the flat portion 201 and the longitudinalsection of the curved portion 202 may range from about 120 degrees toabout 180 degrees.

In FIG. 1 , each of the flat portions 101 and 201 and each of the curvedportions 102, 202 a and 202 b have relatively long edges and relativelyshort edges. Throughout the specification, the longitudinal section ofthe flat portion 201 refers to a relatively long edge or interfacerespectively between the flat portion 201 and each of the curvedportions 202, and the longitudinal section of the curved portions 202refers to the relatively long edge or outermost edge surface of thewindow 200 at a distal end thereof. Longitudinal sections may besimilarly defined for the display panel 100, without being limitedthereto.

Referring to FIG. 2 , within an exemplary embodiment of the window 200,the first angle θ1 formed by the longitudinal section of the flatportion 201 (vertical dotted line) and the longitudinal section of thecurved portions 202 (inclined dotted line) may be about 120 degrees.Referring to FIG. 3 , within a modified exemplary embodiment of thewindow 200, the second angle θ2 formed by the longitudinal section ofthe flat portion 201 (upper portion of vertical dotted line) and thelongitudinal section of the curved portion 202 (lower portion of thevertical dotted line) may be about 180 degrees.

The cross-sectional shape of the curved portions 202 may have a shape asa portion of a circle or portion of an ellipse.

The angle formed by the flat portion 201 and the curved portions 202(e.g., as taken from a distal end of the window 200), may be the sum ofthe angle at which the first curved portion 202 a is curved relative toa virtual line at the interface of the first and second curved portions202 a and 202 b and the angle at which the second curved portion 202 bis curved relative to the longitudinal section of the flat portion 201.The first curved portion 202 a may be curved at an angle ranging fromabout 45 to about 90 degrees with respect to the virtual line at theinterface of the first and second curved portions 202 a and 202 b, andthe second curved portion 202 b may be curved at an angle ranging from45 to 90 degrees relative to the longitudinal section of the flatportion 201.

The window 200 may have substantially the same shape as the displaypanel 100. In an exemplary embodiment, for example, when the displaypanel 100 has the flat portion 101 and the curved portions 102 which arerespectively (lengthwise) extended along the relatively long edges ofthe flat portion 101, the window 200 may have the flat portion 201 andthe curved portions 202 respectively corresponding to the flat portion101 and curved portions 102 of the display panel 100. However, thedisplay device is not limited thereto. In an exemplary embodiment, evenwhen the window 200 includes the flat portion 201 and the curvedportions 202, the display panel 100 may include only the flat portion101. Where the display panel 100 includes only the flat portion 101, thewindow 200 includes a one-side curved portion 202 or two-side curvedportions 202 formed with reference to a single bending line does notintersect another bending line.

FIG. 4A_1 through 4A_4 are perspective views showing processes in amethod of molding a window by using two molds.

The thermal molding of glass for a display device may be performed usingmolds, e.g., an upper mold 401 and a lower mold 402. Additionally, anintermediate mold (not shown) may be employed. The upper mold 401collectively includes four or more partial molds, and the lower mold 402also collectively includes four or more partial molds. FIGS. 4A_1through 4A_4 label a single partial mold as 401 and 402 for convenienceof explanation.

When the concentration of stress occurs due to the intersection of twoor more bending lines or a bending radius is relatively small, at leasttwo molds (upper and lower molds) are used. In a method of pressingglass, a preliminary glass form is heated to a transition pointtemperature or higher, and pressed between molds. The glass heated to atransition point temperature or higher can be relatively easily moldedor shaped.

In the conventional case of a single mold technique in which only onemold is used to deform a preliminary glass form, an internal space ofthe mold is a vacuum or may form a vacuum. As a bending radius of afinally-formed bent window decreases, a force applied to the preliminaryglass becomes higher to form the decreased bending radius. Accordingly,applying the single mold technique to the molding of glass may bedifficult.

Referring to FIGS. 4A_1 and 4A_2, in one or more exemplary embodiment ofa molding technique using at least two molds, a preliminary glassmaterial 200_1 is disposed between the upper and lower molds 401 and402. The preliminary glass material 200_1 is disposed to have portionsextending further than a flat (upper) portion of the lower mold 402 attwo adjacent side surfaces thereof, e.g., at a corner thereof (notvisible in FIGS. 4A_1 and 4A_2, but visible in FIGS. 4A_3 and 4A_4). Thefurther-extended portions of the preliminary glass material 200_1 form acorner portion of a window.

A distance between the upper and lower molds 401 and 402 is decreased(FIG. 4A_1 to FIG. 4A_4) where a portion of the lower mold 402 insertedinto a cavity of the upper mold 401 is respectively increased. As theupper and lower molds are pressed together, interference of thefurther-extended portions of the preliminary glass material 200_1 with amold occurs at corner portions 410 (dotted circle) where a plurality ofbends occur in the preliminary glass material 200_1, and the lengths ofthe corner portions of the preliminary glass material 200_1 increasewhen the upper mold 401 and the lower mold 402 are pressed against eachother (FIG. 4A_3 to 4A_4). The lengths may be taken with respect to adistance from the flat portion of the lower mold 402. Accordingly,implementing a window for a display device in which all four edgeportions thereof are curved to have a desired length and/or uniformityof length a may be difficult.

When the length of the curved portions of the window taken from the flatportion thereof is relatively small, molding of a preliminary glassmaterial is relatively easy. However, the corner portions of thepreliminary glass material are subjected to three-direction bendingsince three bending lines meet one another at each corner of the windowformed from the preliminary glass material.

When a preliminary glass material having a plate shape is molded into a3D object having a curvature, portions of the glass material at thecorner portions thereof overlap each other (dotted circles in FIGS. 4A_3and 4A_4). Furthermore, when a curvature occurs in the plate-shapedpreliminary glass material, rectilinear portions are reduced and thedegree of difficulty regarding bending is increased, and thus molding ofsuch plate-shaped preliminary glass material may be difficult.

FIG. 4B is a view showing a window molded using the method of molding awindow, which is shown in FIGS. 4A_1 through 4A_4.

Edge portions of a preliminary glass material overlap at locations whichform the corner portions of the window, and thus the glass materialextends at the corner portions 420 of the window formed using the methodof molding a window, which is shown in FIGS. 4A_1 through 4A_4.

FIGS. 5A and 5B are perspective views showing shapes of a mold which isused to mold glass.

FIG. 5A shows the shape of a partial upper mold 501 as one quarter of anoverall upper mold which is used to mold glass, and FIG. 5B shows theoverall shape of a collective upper mold 502 defined by a collection ofpartial upper molds 501. When this collectively upper mold is employed,side surfaces and corner portions of a preliminary glass material aresimultaneously molded. Accordingly, problems arise in that portions of apreliminary glass material overlap at the corner portions 510 (dottedline circles). With the overlapping portion of the preliminary glassmaterial, wrinkles are generated and the corner portions are extended(FIG. 4B, as an example). Furthermore, an additional problem arises inthat a shape or profile at a lower end or edge of the molded preliminaryglass material is not controlled (e.g., uneven or non-uniform in length(FIG. 4B, as an example).

FIG. 5C is a top plan view showing a profile of the corner portions 510(dotted line circles) of a window formed from a preliminary glassmaterial. The corner portions 510 of the window in FIG. 5C correspond tothe corner portions 510 of the upper mold 502 in FIG. 5B.

FIG. 6A is a perspective view showing an exemplary embodiment of apartial upper mold which is used to mold glass according to theinvention. The partial upper mold of FIG. 6A may be used in a moldingprocess as generally described in FIGS. 4A_1 through 4A_4, in which alower mold having a preliminary glass material disposed thereon isengaged with the upper mold to deform and curve the preliminary glassmaterial according to a profile of the upper mold.

In an exemplary embodiment, the partial upper mold 601 is a moldcorresponding to one quarter of an overall upper mold. In an exemplaryembodiment, the partial upper mold 601 is formed by engraving adepression into a preliminary partial mold, and the depression includestwo stepped portions, e.g., an upper stepped portion and a lower steppedportion. Furthermore, the depression may include two or more steppedportions.

The partial upper mold 601 includes a window side surface bendingportion 605, a window corner bending portion 615, and a window upperflat portion 625 corresponding to the flat portion of a window. Thewindow upper flat portion 625 comes into contact with a portion of apreliminary glass material which will form the flat portion of thewindow. The window side surface bending portion 605 is located beneaththe window corner bending portion 615 along a thickness direction(vertical in FIG. 6A) of the partial upper mold 601.

Side surfaces of a window formed from a preliminary glass material areprimarily molded using the window side surface bending portion 605 at alower position of the partial upper mold 601, and a corner portion ofthe window is secondarily molded using the window corner bending portion615 at a lower position of the partial upper mold 601 after thecompletion of the side surfaces at the window side surface bendingportion 605.

The depression of the partial upper mold 601 may extend from a lowersurface thereof toward an upper surface thereof, terminating at thewindow upper flat portion 625. The lower surface of the partial uppermold 601 may be disposed in a single plane. The upper flat portion 625may be disposed in a plane parallel to that of the lower surface of thepartial upper mold 601, without being limited thereto.

The window side surface bending portion 605 is inclined with respect tothe lower surface of the partial upper mold 601. The inclined windowside surface bending portion 605 may define a largest planar area of thedepression at the lower surface of the partial upper mold 601. Thus, theinclined window side surface bending portion 605 facilitates the moldingof a glass material heated to a transition point temperature or higherand attachment onto a lower mold.

The window corner bending portion 615 may be defined as a portion of thepartial upper mold 601 between the window upper flat portion 625 and thewindow side surface bending portion 605. A maximum planar area of thedepression at the window corner bending portion 615 is smaller than aminimum planar area defined by the inclined window side surface bendingportion 605. The window corner bending portion 615 of the partial uppermold 601 molds a preliminary material surface in contact therewith afterbeing molded at the window side surface bending portion 605 into acurved surface by further bending the non-curved surface. The windowcorner bending portion of a window mold according to one or moreexemplary embodiments may mold a corner portion of the preliminarymaterial, where one to three bending lines meet one another, into acurved surface.

The generation of a wrinkle and the excessive extension of a lowerportion of the curved surfaces of a window due to overlapping of edgeportions of a preliminary glass material at corner portions thereof maybe reduced or effectively prevented by performing stepwise molding, suchas by using in order, the window side surface bending portion and windowcorner bending portion of the depression.

FIG. 6B is a perspective view showing an exemplary embodiment of anupper mold which is used to mold glass according to the invention. FIG.6C is a cross-sectional view of the partial upper mold of FIG. 6A.

The upper mold of FIGS. 6A through 6C may be used in a molding processas generally described in FIGS. 4A_1 through 4A_4, in which a lower moldhaving a preliminary glass material disposed thereon is engaged with theupper mold to deform and curve the preliminary glass material accordingto a profile of the upper mold.

An upper mold 602 collectively includes four partial molds (601 in FIG.6A). Depressions of the individual partial molds 601 are arranged toform a single one depression of the upper mold 602 at which apreliminary glass material will be curved. Each of the partial moldsincludes a window side surface bending portion 605, a window cornerbending portion 615, and a window upper flat portion 625 configured tocome into contact with a portion of a preliminary glass materialcorresponding to the flat portion of a finally-formed window. The windowcorner bending portion 615 includes an intersection portion 630 at whichthe window corner bending portion 615 transitions to the window upperflat portion 625 and a corner formation portion 640 at which twoadjacent sides of the window corner bending portion 615 meet twoadjacent sides of the intersection portion 630. Within the upper mold602, surfaces of the window side surface bending portion 605, thetransitional portion 620, the window corner bending portion 615, theintersection portion 630 and the window upper flat portion 625 arecoplanar with each other to form continuous surfaces defining a singleone molding cavity of the upper mold 602.

Any one or both of the intersection portion 630 and the corner formationportion 640 may be defined for the partial upper mold 601 depending onthe shape of a finally-formed glass. In an exemplary embodiment, where awindow has a four-sided shape in a top plan view such as the two longersides and the two shorter sides in FIG. 5C, the window may have upper,lower, left, right side surfaces and curved side surfaces at each of thefour sides. The upper, lower, left, and right side surfaces of thewindow are formed from corresponding upper, lower, left, and right sideedge portions of a preliminary glass molded via the window side surfacebending portion 605. The preliminary glass material heated to atransition point temperature or higher is pressed onto the window sidesurface bending portion 605 of the partial upper mold 601 to be curvedthereby.

A transitional portion 620 of the partial upper mold 601 is an area atwhich the window side surface bending portion 605 transitions to thewindow corner bending portion 615. The transitional portion 620 isdisposed above the window side surface bending portion 605 in adirection toward the window upper flat portion 625. The transitionalportion 620 facilitates the bending of side surfaces of the preliminaryglass material, promotes entry onto the window corner bending portion615 from the window side surface bending portion 605, and is bent at apredetermined angle different from that of the window side surfacebending portion 605. A planar area or cross-sectional dimension of thedepression at the transitional portion may be between that at the windowside surface bending portion 605 and a remainder of the window cornerbending portion 615. That is, a planar area or cross-sectional dimensionof the depression may decrease from a lower surface of the upper mold602 toward the upper flat portion 625.

When a thermal molding target glass material is applied into thedepression and onto the window side surface bending portion 605 such asfrom outside the upper mold 602, the side surfaces at end portions ofthe target glass material are bent according to the inclined angle ofthe window side surface bending portion 605. Since the molding of theside surfaces is completed on the side surfaces of the window sidesurface bending portion, the concentration of the target glass materialonto the corner portions is eliminated. The molding of the side surfacesexcept for the corner portions is performed by the window side surfacebending portions 605 of the four partial upper molds 601, Thus, theupper, lower, left and right side surfaces and the corner portions of awindow are simultaneously molded by the collective upper mold 602,thereby reducing or effectively preventing a wrinkle from beinggenerated on the corner portions and also reducing or effectivelypreventing the length of the side surfaces of the window from beingchanged from an original length thereof.

When the molding of the upper, lower, left and right side surfaces ofthe thermal molding target glass material is finished on the window sidesurface bending portion 605, the thermal molding target glass materialis transitioned within the upper mold 602 to the window corner bendingportion 615 by passing over the transitional portion 620.

When the molded thermal target glass is raised within the depressionfrom the window side surface bending portion 605 to the window cornerbending portion 615, ends of the molded thermal target glass is disposedabove the transitional portion 620 such that the transitional portion620 below the raised glass does not overlap the ends thereof.

The transitional portion 620 has a slope steeper than that of the windowside surface bending portion 605 relative to the lower surface of theupper mold 602, facilities the entry of the upper, lower, left and rightside surfaces, previously molded on the window side surface bendingportion 605, onto the window corner bending portion 615, and enables theupper, lower, left and right side surfaces to be securely fastened alongsurfaces of the upper mold 602.

Furthermore, the transitional portion 620 reduces or effectivelyprevents glass having entered onto the window corner bending portion 615from flowing downward.

The width (e.g., overall planar area) of the previously molded glasshaving entered onto the window corner bending portion 615 is decreasedsince the planar area or cross-sectional dimension of the depression atthe window corner bending portion 615 is smaller than that of each ofthe transitional portion 620 and the window side surface bending portion605. With the decreased size of the previously molded glass havingentered onto the window corner bending portion 615, the upper, lower,left and right side surfaces at ends of the previously molded glass arebrought into tight contact with each other, and an obtuse angle of thepreviously molded glass formed on the window side surface bendingportion 605 is changed vertically to be inclined at an angle less thanthe first obtuse angle.

The previously molded glass is pressed by the window corner bendingportion 615 and the upper flat portion 625 after the window sidesurfaces have been molded by the window side surface bending portion605, thereby being molded into the corners and upper portion of thefinally-formed window.

The intersection portion 630 where upper flat portion 625 and windowcorner bending portions 615 surfaces intersect one another inside themold has a predetermined curvature and a predetermined thickness so thata portion of a finally-formed window where flat portion and curvedportion surfaces intersect one another have the predetermined curvatureand the predetermined thickness corresponding to those of the upper mold602.

Furthermore, at corners 610 of the upper mold 602, the corner formationportion 640 forms corners of the finally-formed window at an area whichthree surfaces of the target glass material are brought into contactwith one another by bending end portions thereof along three bendinglines.

The corner formation portion 640 may have a curvature and a thicknessidentical to or different from those of the intersection portion 630.

The side surfaces of the glass material raised from the window sidesurface bending portion 605 are made vertical (e.g., substantiallyperpendicular to the lower surface of the upper mold 602) by the windowcorner bending portion 615, and are brought into contact with each otherwithin the upper mold 602 with the window corner bending portion 615thereof.

Since the upper, lower, left and right side surfaces of a finally-formedwindow are all formed at the window side surface bending portion 605,only the corners are formed on the window corner bending portion 615.The target glass material to be deformed on the window side surfacebending portion 605 enters onto the window corner bending portion 615 inthe state of being spread at a predetermined angle, and thus theconcentration of tensile stress onto the corners is reduced, therebyreducing a decrease in the thickness of corner portions and thegeneration of wrinkles. Furthermore, differences in height or thicknessof the curved portions of the finally-formed window may be eliminated atthe portions thereof except for the corners and the corner portions.

According to the prior art, an extension phenomenon occurs at eachcorner portion, and thus the work of reducing a length such as byshaving of the surfaces of the corner portions is required to eliminatedifferences in height. In contrast, one or more exemplary embodiment offorming a window and a mold used therefor obviates the separate work ofshaving surfaces or lengths.

FIGS. 7A and 7B are perspective and top plan views showing an exemplaryembodiment of a window molded using a method of molding a windowaccording to the invention. Referring to FIG. 7A, it can be seen thatthe method of molding a window according to one or more exemplaryembodiment of the invention does not generate a decrease in thethickness, a wrinkle, an increase in the difference in length, etc. atcorner portions 710 of the window.

Referring to FIG. 7B, it can be seen that when the method of molding awindow according to one or more exemplary embodiment of the invention,the generation of a wrinkle and an increase in the difference in lengthof the curved side surface of the window in a direction away from theflat portion thereof may be reduced or prevented at the corner portionsof the finally formed window.

FIG. 8 is a perspective view showing a bending line 820 provided inplurality and intersecting one another at a corner portion of afinally-formed window. The bending lines 820 intersect one another atthe corner portion of the finally-formed window. Three bending linesintersect one another at the corner portion of the finally-formedwindow. In an exemplary embodiment, the three bending lines 820respectively lengthwise extend along the first, second and thirddirections.

FIGS. 9A to 9D respectively show exemplary embodiments of amulti-surface corner glass window molded using the method according tothe invention.

Referring to FIGS. 9A and 9B, triangular and pentagonal glass windowsmay include corner portions 910 and 1010. In one or more exemplaryembodiment of a method of forming a window and an upper mold usedtherefore, the corner portions 910 and 1010 may be freely formed, suchas from a rectilinear preliminary glass window.

FIG. 9C shows a curved corner which is formed at a portion 1110 wheretwo side surfaces at two adjacent sides of a flat portion intersect eachother, while side surfaces are absent at remaining sides of the flatportion.

FIG. 9D is a view showing a corner portion molded to include a recess inthe side surface extended from a flat portion.

Referring to FIG. 9D, a window may be molded such that an empty space isformed recessed from an end edge of the window at a window corner 1210.The space may not be recessed from the end edge to a flat portion and anupper portion of the side surface at the window corner 1210 may remainto have a predetermined length from the flat portion.

In this case, the predetermined length of the window at the windowcorner 1210 may be about 1 millimeter (mm) or more taken from a sideedge of the flat portion toward the end edge of the window.

The above-described method of implementing a multi-surface 3D displaydevice according to one or more exemplary embodiment of the invention isused to mold a glass window capable of covering and protecting fivesurfaces of a display device, including a front (display) surface andside surfaces extended curved therefrom including at corners of thedisplay device, by using a preliminary glass having a plate shape.

Furthermore, there may be implemented a display device having afour-side edge display in which glass corner portions are present atcorners of the display device and the degree of completion of design ishigh.

One or more exemplary embodiment of the method of molding a window for adisplay device to have curved side surfaces extended from a displaysurface according to the present disclosure is capable of forming curvedcorners without elongating or thinning, wrinkling or cracking thepreliminary glass material.

A phenomenon in which the corner portions are lengthwise extended doesnot occur, and thus an additional process for trimming the extra lengthis obviated.

Although the exemplary embodiments of the present disclosure have beendescribed with reference to the accompanying drawings, it will beunderstood by those having ordinary knowledge in the art to which theinvention pertains that the invention may be practiced in other specificforms without departing from the technical spirit and essential featuresof the invention. Therefore, the above-described exemplary embodimentsshould be understood as being illustrative, not limitative, in allfeatures.

What is claimed is:
 1. A method of molding a window for a displaydevice, the method comprising: providing curved side surfaces and acurved corner of the window which respectively correspond to sidesurfaces and a corner of the display device, by pressing a preliminarywindow glass which is heated to a transition point temperature or higherto define a heated preliminary window glass to at least one mold of anupper mold and a lower mold, wherein the at least one mold comprises: alower surface; and a depression extended from the lower surface anddefined in order from the lower surface by: a window side surfacebending portion extended directly from the lower surface andcorresponding to the side surfaces of the display device which arerespectively extended from edges of a flat display portion thereof; awindow corner bending portion extended inclined from the window sidesurface bending portion and corresponding to the corner of the displaydevice which is extended curved from a corner of the flat displayportion thereof; and a flat portion corresponding to the flat displayportion of the display device, wherein with respect to the lowersurface: the window side surface bending portion is inclined at a firstangle which is an obtuse angle, and the window corner bending portion isinclined at a second angle smaller than the first angle; the providingthe curved side surfaces of the window comprises pressing the heatedpreliminary window glass against the window side surface bending portionof the at least one mold; and after the providing of the curved sidesurfaces, providing the curved corner and a flat portion of the windowby further pressing the heated preliminary window glass respectivelyagainst the window corner bending portion and the flat portion of the atleast one mold.
 2. The method of claim 1, wherein the window sidesurface bending portion of the at least one mold comprises an inclinedsurface, and the pressing of the heated preliminary window glass againstthe window side surface bending portion presses an end portion of theheated preliminary window glass against the inclined surface to bend theend portion at the first angle and define a bent end portion of theheated preliminary window glass.
 3. The method of claim 2, wherein thefurther pressing of the heated preliminary window glass against thewindow corner bending portion comprises contacting the bent end portionof the heated preliminary window glass along the window corner bendingportion to further bend the end portion to be curved at the secondangle.
 4. The method of claim 1, wherein the at least one mold furthercomprises a plurality of partial molds each including the flat portionof the at least one mold, the window side surface bending portion andthe window corner bending portion.
 5. The method of claim 1, wherein alargest cross-sectional width of the depression is defined at the windowside surface bending portion of the at least one mold, the preliminarywindow glass being inserted into the at least one mold through thelargest cross-sectional width of the depression which is defined at thewindow side surface bending portion.